Oil to Gas Conversion Options

Hot_water_fan

Yes. Your heat loss is much lower than the output of that boiler. And the tank stores energy for periods of high demand and the indirect will have priority. That’s a pretty big boiler. If you lived anywhere else in the country, a contractor would install a hot water tank + furnace with substantially less total capacity with none of the drama. 

David_16

@Hot_water_fan It's nuts, but every single contractor was oversized. Some others said ES4+indirect would be fine and this is a bit more than ES4, so I'm not particularly worried. At least with modcon, it's not costing me as much gas even if I went with the 150-H, which I'm not doing. Had a long conversation with the contractor and he'll do the 110-H somewhat reluctantly and will support it, but if I call and say it's not going over 65 in the house on frigid day, he's going to push back a bit. I suppose there could be other reasons the house isn't fully heating up that he would need to support, right? Like imperfect programming with the boiler or outdoor reset that he still should look at before throwing his hands up at me and telling me to look at what I signed?

EBEBRATT-Ed

You will be fine. If set up properly there is no need to oversize for adding an indirect.

KC_Jones

David_16 said:

@Hot_water_fan It's nuts, but every single contractor was oversized. Some others said ES4+indirect would be fine and this is a bit more than ES4, so I'm not particularly worried. At least with modcon, it's not costing me as much gas even if I went with the 150-H, which I'm not doing. Had a long conversation with the contractor and he'll do the 110-H somewhat reluctantly and will support it, but if I call and say it's not going over 65 in the house on frigid day, he's going to push back a bit. I suppose there could be other reasons the house isn't fully heating up that he would need to support, right? Like imperfect programming with the boiler or outdoor reset that he still should look at before throwing his hands up at me and telling me to look at what I signed?

They can still install it incorrectly. Most of the problems we see around here are due to the contractor messing up the install, actually probably close to 100% of what we see around here is the contractor.

And all the ones you are calling can't even understand step 1, sizing. Not trying to scare you, but as a homeowner, knowing what I do, I'd be nervous.

EBEBRATT-Ed said:

You will be fine. If set up properly there is no need to oversize for adding an indirect.

That bold is very important.

jesmed1

If it makes you feel any better, I maintain a 4-unit, 4800-sq-ft, 100 year old condo building in the Boston suburbs, and that boiler could heat this entire building and supply the hot water too for all 4 units.

David_16

KC_Jones said:

They can still install it incorrectly. Most of the problems we see around here are due to the contractor messing up the install, actually probably close to 100% of what we see around here is the contractor.

And all the ones you are calling can't even understand step 1, sizing. Not trying to scare you, but as a homeowner, knowing what I do, I'd be nervous.

EBEBRATT-Ed said:

You will be fine. If set up properly there is no need to oversize for adding an indirect.

That bold is very important.

Fair and I understand. Would I be any less nervous going with the 150-H? Could the extra size compensate if they did install it incorrectly. Or 110 vs 150, isn't going to matter much in that case?

KC_Jones

David_16 said:

KC_Jones said:

They can still install it incorrectly. Most of the problems we see around here are due to the contractor messing up the install, actually probably close to 100% of what we see around here is the contractor.

And all the ones you are calling can't even understand step 1, sizing. Not trying to scare you, but as a homeowner, knowing what I do, I'd be nervous.

EBEBRATT-Ed said:

You will be fine. If set up properly there is no need to oversize for adding an indirect.

That bold is very important.

Fair and I understand. Would I be any less nervous going with the 150-H? Could the extra size compensate if they did install it incorrectly. Or 110 vs 150, isn't going to matter much in that case?

If they pipe it wrong, the size doesn't matter, it's still wrong and may not perform properly.

Your system isn't capable of more than ~78,000 btu, that's it. No matter how much you try and pump into it you get out 78,000 btu, that's the facts of what you have. The limit is the baseboard. So, any boiler output beyond that is 100% waste, which then forces the boiler to cycle as the system can't take the btu's.

Hot_water_fan

 I suppose there could be other reasons the house isn't fully heating up that he would need to support, right? Like imperfect programming with the boiler or outdoor reset that he still should look at before throwing his hands up at me and telling me to look at what I signed?

Yes if your house is cold, I’m certain it won’t be the sizing. Any number of things can happen unrelated to the boiler size. You’re putting a boiler in 2x the heat load. 3x doesn’t help anything. 45-50 Btu/sqft is HUGE. 

David_16

Hot_water_fan said:

 I suppose there could be other reasons the house isn't fully heating up that he would need to support, right? Like imperfect programming with the boiler or outdoor reset that he still should look at before throwing his hands up at me and telling me to look at what I signed?

Yes if your house is cold, I’m certain it won’t be the sizing. Any number of things can happen unrelated to the boiler size. You’re putting a boiler in 2x the heat load. 3x doesn’t help anything. 45-50 Btu/sqft is HUGE. 

Makes sense. Appreciate all of the input.

In the end, I'm happy with the modcon+indirect solution. I could have gone CI+indirect and maybe it'll have lasted longer and will be less maintenance over time, but this should save me some gas along the way as well and make for a very neat install and no need to re-line my chimney. The $1400 rebates from National Grid (for 2023 and hopefully at least that when they install in 2024) and $600 tax credit make a big difference as well. CI+indirect only nets like $675 total rebates.

LRCCBJ

David_16 said:

You guys are all sure 90-100K output (depending on efficiency it's running at) is more than sufficient to heat 2000 square foot house with 141 feet of baseboard and power the indirect to deliver enough hot water for like 2 showers at once or 1 shower running for a long time?

The boiler is oversized for the CH load.

However, the answer to whether we are SURE it is sufficient for your hot water demands required the answer to the following questions:

1) What is the flow rate from the shower heads?
2) What is the definition of "a long time".

A 45 gallon indirect does have a time limit before the reserve is exhausted and the boiler itself must continue to produce sufficient hot water.

As an example, if you take two simultaneous showers with a flow rate of 3GPM in each shower, you'd have somewhere between 10 and 15 minutes before you both run out of hot water. The variable is due to the incoming cold water temperature AND the temperature of the stored water in the indirect.

As another example, if you have one shower with a flow rate of 2.5 GPM, you can probably run it indefinitely as the boiler should just barely keep up.

As a side note, all the installers wish to add the CH load together with the DHW load so that, in theory, you can heat the house simultaneously with taking a continuous shower. This is a bit unrealistic as the shower lasts 30 minutes or so and the CH is off during that period. You probably would never notice the fact that you have no CH when someone is taking a shower.

As an additional side note:

The proper way to manage heavy hot water demand is NOT with a larger boiler, which you pay for. It is with a larger INDIRECT where you store sufficient hot water for your needs.

David_16

LRCCBJ said:

David_16 said:

You guys are all sure 90-100K output (depending on efficiency it's running at) is more than sufficient to heat 2000 square foot house with 141 feet of baseboard and power the indirect to deliver enough hot water for like 2 showers at once or 1 shower running for a long time?

The boiler is oversized for the CH load.

However, the answer to whether we are SURE it is sufficient for your hot water demands required the answer to the following questions:

1) What is the flow rate from the shower heads?
2) What is the definition of "a long time".

A 45 gallon indirect does have a time limit before the reserve is exhausted and the boiler itself must continue to produce sufficient hot water.

As an example, if you take two simultaneous showers with a flow rate of 3GPM in each shower, you'd have somewhere between 10 and 15 minutes before you both run out of hot water. The variable is due to the incoming cold water temperature AND the temperature of the stored water in the indirect.

As another example, if you have one shower with a flow rate of 2.5 GPM, you can probably run it indefinitely as the boiler should just barely keep up.

As a side note, all the installers wish to add the CH load together with the DHW load so that, in theory, you can heat the house simultaneously with taking a continuous shower. This is a bit unrealistic as the shower lasts 30 minutes or so and the CH is off during that period. You probably would never notice the fact that you have no CH when someone is taking a shower.

As an additional side note:

The proper way to manage heavy hot water demand is NOT with a larger boiler, which you pay for. It is with a larger INDIRECT where you store sufficient hot water for your needs.

Excellent answer and this is all the exact conclusion I've come to based on all of the other posts to date. Installer wanted to go 1 boiler size larger, but he agreed to this one if I sign that I chose the size. Going one smaller, I'm not sure. With this being a modcon, oversizing not hurting me too bad as I understand things. The 150-H to 110-H was a bigger drop in price than I expected. Don't think going from 110-H to 80-H will save me too much up front, so I'm good.

If I can do 2 3GPM showers at the same time for 10 minutes, that's fine. We rarely even take 2 showers. I'm resigned to the fact that billing the 60-70 gallon tub is going to have to be done in stages, like it is now.

hot_rod

A 40 gallon indirect at 145F will give you over 509 gallons od DHW if you add a mixing valve.
This give you the extra capacity and elevated temperature in the tank for legionella prevention.

You probably don' fill the tub with 120F, so this should fill a 60 gallon tub.

Here is the calculator if you want to use your actual numbers, like incoming water temperature.
https://www.lochinvaru.com/resource/calculator/storagetankMixingCal.html

David_16

hot_rod said:

A 40 gallon indirect at 145F will give you over 509 gallons od DHW if you add a mixing valve.
This give you the extra capacity and elevated temperature in the tank for legionella prevention.

You probably don' fill the tub with 120F, so this should fill a 60 gallon tub.

Here is the calculator if you want to use your actual numbers, like incoming water temperature.
https://www.lochinvaru.com/resource/calculator/storagetankMixingCal.html

That's helpful. The new indirect will actually be 45 gallons. I guess I'll find out in a few weeks! Today, I have a 40 gallon tank and no mixing valve and the tub probably doesn't even get half full before it runs out. It does recover within a matter of minutes and then i add maybe another 10 gallons, wait a few more minutes and another 10, etc. It's a bit of a pain. Would be easier if I had a tub that I can restrict the flow on, but mine doesn't work that way.

David_16

Again, thanks for everyone's help so far, I've learned so much.

I'm still waiting for the gas permit to be granted and the plumber to give me an install date for my new Weil-McLain ECO Tec 110 and 45 gallon indirect with my hot water baseboard system.

In the meantime, I have a few more questions.

Today with my oil fired cast iron, I sometimes find the heat to not be "steady". Like when it kicks in, it sometimes gets too hot and even overshoots the thermostat a bit. Will the modcon work any differently? Is this something my plumber can adjust if I provide this kind of input?

What other homeowner type questions should I be asking (or preferably them asking me) before/during install? Like are there 10 different ways to program the boiler limits or the outdoor reset depending on how I like things? Like is there one way to program it that will heat up the house faster on a cold day vs heating up the house more slowly, but in a more comfortable way?

I don't have a mixing valve on my indirect today and will with the new system. This may be a dumb question, but do I need to manually recalibrate the maximum hot in any single knob faucets that I have? I know my shower has some sort of "stopper" control inside the handle that I've adjusted before. Because if old indirect is sending up say 130 degree water and the new one is sending up 120 degree water, I'm thinking the single handle faucet might need to mix in more hot water than currently is possible. I'm probably way off on this one, but am curious.

Any other types of considerations and questions that I should go over with them prior to completing the installation?

hot_rod

You might download the manual for the boiler you are getting and start reading about how the control works. Learn about the various settings to fine tune it to your system.

You should not need to calibrate the faucets.

Many owners maintain the tank at 140 for bacteria protect. Then add a mix valve to set to 120F.

This give you more hot water drawdown, and temperature protection at the faucets.

Jamie Hall

The unsteadiness in temperature or the overshoot, may also be related to your thermostat and the way it interacts with the way your house heats. This may require some tweaking after the install.

David_16

Wow, I caught a really bad break here.

National Grid seems to have ended their rebate program and there's no longer an $1100 rebate for the Eco Tec in 2024. There should still be an IRS $600 tax credit that I can get.

I had the company I'm going to do the install give me a quote for a CI option.

Without the $1100 rebate and after the $600 IRS credit, the 2 options are nearly identical in price.

Installer has proposed a Weil-McClain CGa (I requested he use the CGa-4). He says he prefers the CGa over the Burnham ES2 that a lot of companies around here were proposing.

Now, I've got to make a final decision. When the Eco Tec was $1100 less, I was definitely going that route, but now I'm reconsidering.

First of all, how is the CGa, in general? Is it fairly equivalent to the ES2? CGa itself seems to cost a good bit less than the ES2 from what I can tell.

I guess my thinking is that odds are the CGa will last longer than the Eco Tec and the lower maintenance (both things breaking and maybe not needing someone to come every year) will much more than offset any fuel savings realized from the Eco Tec, especially since I have baseboard and the Eco Tec will not condense a good part of the time.

Thoughts?

Steamhead

The CGa and ES2 are fairly comparable. Both have been around for a while in different versions and I see a lot of older ones. I'd say you can't go wrong either way.

David_16

Steamhead said:

The CGa and ES2 are fairly comparable. Both have been around for a while in different versions and I see a lot of older ones. I'd say you can't go wrong either way.

Good to know on CGa vs ES2, but what about CI vs modcon where I'm at at this point?

Steamhead

David_16 said:

Good to know on CGa vs ES2, but what about CI vs modcon where I'm at at this point?

CI. Simpler, longer lasting, less trouble, parts more readily available if needed. Make sure your contractor knows their stuff, however.

David_16

Even without the rebate, I decided to stick with the Weil McLain Eco Tec 110 with WM indirect. I just had to get over the fact that it's still a good option.

PeteA

David_16 said:

Even without the rebate, I decided to stick with the Weil McLain Eco Tec 110 with WM indirect. I just had to get over the fact that it's still a good option.

@David_16
isnt that Eco TEC a combi? What’s the reason for the indirect?

David_16

PeteA said:

David_16 said:

Even without the rebate, I decided to stick with the Weil McLain Eco Tec 110 with WM indirect. I just had to get over the fact that it's still a good option.

@David_16
isnt that Eco TEC a combi? What’s the reason for the indirect?

No, it comes in a heat only version too. My new indirect is a warranty replacement so I'm only paying for install.